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dhondtadhondta
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Added new codec: shift
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‎README.md‎

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@@ -29,6 +29,7 @@ This library extends the native `codecs` library and provides some new encodings
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`radio` | Radio <-> text | aka NATO or radio phonetic alphabet
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`resistor` | Resistor <-> text | aka resistor color codes
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`rot-N` | ROT(N) <-> text | aka Caesar cipher (N belongs to [1,25])
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`shift` | shift(N) <-> text | shift ordinals with N (belongs to [1,255])
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`url` | URL <-> text | aka URL encoding
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`xor-N` | XOR(N) <-> text | XOR with a single byte (N belongs to [1,255])
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`whitespace` | Whitespaces <-> text | replaces bits with whitespaces and tabs

‎codext/VERSION.txt‎

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1.4.3
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1.4.4

‎codext/crypto/__init__.py‎

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from .bacon import *
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from .barbie import *
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from .rotn import *
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from .shift import *
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from .xor_byte import *

‎codext/crypto/shift.py‎

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# -*- coding: UTF-8 -*-
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"""Shift-N Codec - Shift-ordinal-with-N content encoding.
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This codec:
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- en/decodes strings from str to str
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- en/decodes strings from bytes to bytes
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- decodes file content to str (read)
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- encodes file content from str to bytes (write)
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"""
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from ..__common__ import *
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def ord_shift_decode(i):
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return ord_shift_encode(-i)
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def ord_shift_encode(i):
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def encode(text, errors="strict"):
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r = "".join(chr((ord(c) + i) % 256) for c in text)
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return r, len(r)
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return encode
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add("shiftN", ord_shift_encode, ord_shift_decode,
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r"(?i)(?:ord(?:inal)?[-_]?)?shift[-_]?([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$")

‎docs/ciphers.md‎

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@@ -130,6 +130,27 @@ This is a dynamic encoding, that is, it can be called with an integer to define
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-----
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### Shift
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This is a dynamic encoding, that is, it can be called with an integer to define the shift offset. Encoding will apply a positive offset, decoding will apply a negative one.
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**Codec** | **Conversions** | **Aliases** | **Comment**
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:---: | :---: | --- | ---
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`shiftN` | shift(1) <-> text | `shift1`, `shift-1`, `shift_1` |
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`shiftN` | shift(X) <-> text | ... |
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`shiftN` | shift(255) <-> text | `shift255`, `shift-255`, `shift_255` |
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```python
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>>> codext.encode("this is a test", "shift-3")
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'wklv#lv#d#whvw'
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>>> codext.decode("wklv#lv#d#whvw", "shift10")
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'mabl\x19bl\x19Z\x19m^lm'
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>>> codext.encode("mabl\x19bl\x19Z\x19m^lm", "ordshift_7")
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'this is a test'
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```
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-----
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### XOR with 1 byte
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This is a dynamic encoding, that is, it can be called with an integer to define the ordinal of the byte to XOR with the input text.

‎tests/test_shift.py‎

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#!/usr/bin/env python
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# -*- coding: UTF-8 -*-
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"""Shift codecs tests.
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"""
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import os
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from six import binary_type, string_types
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from unittest import TestCase
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from codext.__common__ import *
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class TestCodecsShift(TestCase):
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def test_codec_shift(self):
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STR = "this is a test"
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SH1 = "uijt!jt!b!uftu"
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SH9 = "}qr|)r|)j)}n|}"
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TFILE = "test-codec-shift.txt"
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self.assertTrue(isinstance(codecs.encode(STR, "shift-200"), string_types))
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self.assertEqual(codecs.encode(STR, "shift_1"), codecs.decode(STR, "shift_255"))
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self.assertEqual(codecs.encode(STR, "ord-shift_1"), SH1)
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self.assertEqual(codecs.encode(STR, "ordinal_shift-1"), SH1)
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self.assertEqual(codecs.encode(STR, "shift1"), SH1)
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self.assertEqual(codecs.encode(STR, "ordshift1"), SH1)
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self.assertEqual(codecs.encode(STR, "ordinalshift1"), SH1)
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self.assertEqual(codecs.encode(STR, "shift_9"), SH9)
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self.assertEqual(codecs.encode(STR, "ord_shift_9"), SH9)
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self.assertEqual(codecs.encode(STR, "ord-shift-9"), SH9)
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self.assertEqual(codecs.decode(SH1, "shift1"), STR)
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self.assertRaises(LookupError, codecs.decode, STR, "shift0")
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self.assertRaises(LookupError, codecs.decode, STR, "shift--10")
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self.assertRaises(LookupError, codecs.decode, STR, "shift256")
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self.assertRaises(LookupError, codecs.decode, STR, "shift300")
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s = STR
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for i in range(1, 256):
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old = s
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s = codecs.encode(s, "shift1")
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self.assertEqual(codecs.decode(s, "shift1"), old)
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self.assertTrue(not PY3 or isinstance(codecs.encode(b(STR), "shift1"), binary_type))
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with codecs.open(TFILE, 'w', encoding="shift-1") as f:
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f.write(b(STR))
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with open(TFILE) as f:
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r = f.read().strip()
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self.assertEqual(SH1, r)
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with codecs.open(TFILE, encoding="shift-1") as f:
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s = f.read().strip()
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self.assertEqual(STR, ensure_str(s))
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os.remove(TFILE)

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